fix bug

Former-commit-id: 7845ac1cfa57cb3d8dd7d81f175810f97d629499

src/containers/popupMenu/component.tsx

@@ -8,7 +8,7 @@ import { PopupMenuProps, PopupMenuStates } from "./interface";
 
 declare var window: any;
 
-let _ = window.lodash;
+let _ = window._;
 
 class PopupMenu extends React.Component<PopupMenuProps, PopupMenuStates> {
   highlighter: any;

src/index.tsx

@@ -15,4 +15,4 @@ ReactDOM.render(
 // If you want your app to work offline and load faster, you can change
 // unregister() to register() below. Note this comes with some pitfalls.
 // Learn more about service workers: https://bit.ly/CRA-PWA
-serviceWorker.register();
+serviceWorker.unregister();

src/utils/backupUtil.tsx

@@ -8,7 +8,7 @@ import DropboxUtil from "./syncUtils/dropbox";
 import OndriveUtil from "./syncUtils/onedrive";
 // import _ from "lodash";
 
-let _ = (window as any).lodash;
+let _ = (window as any)._;
 let JSZip = (window as any).JSZip;
 class BackupUtil {
   static backup(